Time control for stokers



Oct. 14, 1930. T. H. BANFIELD TIME CONTROL FOR STOKERS Filed April 28, 1928 Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE anon-Asia BANr' mLD, or PORTLAND, OREGON TIME CONTROL FOR STOKERS Application filed April as,

\ vide a time controlfor the stoker whereby the fire will be automatically maintained whether or'n'o there are calls for heat from the point of delivery, or from the point of storage if a heat storing element such as a boiler is included in the heating system.

Thesecond object isto make it possible to successfully use very small stokers in which the coal bed is of a size which would become a completely extinguished if it were notperi- 15 air.

odically renewed by't he addition of fuel and These, and other objects, will become more apparent from the specification following as illustrated in the accompanying drawing, in which:

Figure 1 is a somewhat diagrammatic view of-a stoker and a control mechanism. Figure 2 is an elevation of arepresentative form of time clock taken along the line 22, in Fig, ure 1. Similar numbers of reference refer to similar parts throughout the views.

Referring in detail to the drawing, there is illustrated the usual form of boiler under which is inserted aretort 11 to which coal 12 a is fed through a fuel feed duct 13 from the I hopper 14 by a motor15 operating through a reduction gear enclosed within a casing 16. The motor also operates a fan enclosed within a casing 17 which, through the duct 18, deliv-. ers a supply of air to the tuyeres of the'retort 11. A highpressure air pipe 19 delivers air into the fuel feed duct 13 to prevent gassing generating element. There is also indicated a fioor 20 of a room in which is placed a radia- I tor 21 connected to the boiler 10 by means of the pipe 22. The room in which the radiator I 21 is placed is also provided with a thermostat 23, and the boiler 10 is provided with an automatic switch 24, which may be of any'of those types now in use, and can be operated either 'noids 44 and 45 having 1928. Serial in). 273,707.

with pressure or temperature. There is also provided an electrically operated switch 25 by means of which the flow of current from the power line 26 to the motor 15 can be controlled. A transform'er 27 is also provided across the power line 26.

One wire 28 from the transformer 27 connects with the switch 24 and the other wire 29 connects the transformer 27 with the thermostat 23. A time clock 30 is also provided .The brush 37 is attached by means of the wire 42 to the wire 29, and the brush 39 is joined by means of the wire 43 to the wire 28.

The switch 25 is operated by a pair of solewhich is attached to the switch 25. One wire 47 of the solenoid 44 connects with one side of the switch 24, and the other wire 48 of the solenoi'd 44 is joined to one side of the thermostat 23. One side of the solenoid is joined by means of a wire 49 to the switch 24, and the other side of'the solenoid 45 is joined by means of the wire 50 to the remaining side of the thermostat 23. A wire 48 is connected to the brush 38 by means of the wire 51. The wire 43 connects the brush 39- with the wire 28, and the wire 52 connects the brush 40 with the wire 47.

The operatiomof the device is as .follows: It is assumed that'the hopper 14 contains coal and that a fire has been started within the retort 11 which, having been started, will burn for a given length of time without outside assistancethat is to say, there will remain a bed of coals which requiresonly the addition of more fuel and a blast of air to build it up to a point where it will be giving off heat and will again burn for a given length of time.

It will be understood that with automatically controlled stokers the fire must never die out completely, otherwise when the 0on trols become operative and call upon the stoker for heat that there must be a bed of a common core 46 live coals present before the device can function. The function of the time clock is to preserve this bed of coals. The function of the switch 24 is to maintain a supply of heat in the reservoir or boiler. 10 to meet a sudden demand. The function of the thermostat 23 is to call upon the boiler for some of its heat whenever the temperature of the room falls below a predetermined minimum.

With these functions in mind it will be seen that with the room thermostat 23 set to close its side of the motor circuit when the room temperature falls below a predetermined minimum, and the automatic switch 24 set to close its side of the motor operat ing circuit when the amount of heat stored falls below a predetermined minimum, then it can be seen that a joint functioning of the elements 23 and 24, indicating a need for heat, will start the motor 15 independently of the time clock 30. If, however, there should be no calls for heat, either at the room or at the boiler for a period of time which exceeds that at which a bed of coals will remain alive within the retort 11, then the fire would be extinguished and when the call for heat finally did come the result would be the forcing of unburned coal up through the retort, which would obviously be undesirable.

However, by means of this device, before a space of time has elapsed in which the fire can become extinguished the time clock 30, acting either through the contacts 32 and 33 or the contacts 34 and 35-, depending upon which group of contacts is selected under the control of the plunger 41, will close the motor circuit around the instruments 23 and 24that is to say the contact 32 will close the circuit across the brushes 37 and 38 and shunt the circuit around the thermostat 23. The contacts33 which engages the brushes 39 and 40, will shunt the circuit around the instrument 24, or if more frequent operations are required, the brush holder 36 is moved in order that the brushes 37 and 38 will register with the contact 34, and the brushes 39 and 40 will register with the contact 35. The contacts 34 and 35 being more in number than the contacts 33 and 34, will obviously provide more frequent operations for the motor 15.

Obviously, any number of contacts may be provided to suit the particular requirements without departing from the spirit of this invention.

I claim:

1. In a furnace; a motor driven stoker, means for periodically closing the motor circuit, and two spaced thermostats adapted to close the motor circuit independently of said means.

2. In combination; a furnace, a stoker, time controlled means for operating the stoker to supply fuel and air to the furnace fordefinite periods of time at chosen intervals and irrespective of temperature requirements, a room thermostat; a furnace thermostat, and means connecting the room thermostat and boiler thermostat in series to continue the feeding of fuel and air to the furnace after the close of the fuel feeding period when the heat requirements have not been met.

3. In combination, a furnace, a stoker, time controlled means for operating the stoker to supply fuel and air to the furnace at definite periods of time irrespective of temperature requirements, a room thermostat, a furnace thermostat, and electric means connecting the room thermostat and boiler thermostat to continue the feeding of fuel and air to the furnace after the close of the periodic feeding whenever the heat requirements have not been met, and means operated by the room thermostat and the boiler thermostat conjointly for interrupting the feed of fuel and air to the furnace when the heat requirements have been met.

4. In a furnace, a motor operated stoker, a motor circuit, a control circuit, a switch in said control circuit for opening and closing the motor circuit, a thermostat in said control circuit located in the room to be heated, a furnace temperature or pressure responsive device in the control circuit, said room device and said furnace device cooperating to make and to break the motor circuit dependent upon the temperature in the room and the temperature or pressure of the furnace, and time controlled mechanism inde- 10o pendent of the room and furnace devices for closing the motor circuit switch at chosen intervals, said time controlled mechanism being rendered inoperative when the room and furnace temperatures exceed the chosen max- 5 imum, and being unnecessary when the room and furnace temperatures fall below the chosen minimum since in the latter case the thermostats will have closed the motor switch to cause the stoker to feed fuel to 110 the furnace. I

5. In a system for heating a room from a distant furnace, a motor operated fuel feeding device, a motor circuit, an electric control circuit for intermittently closing the 115 motor circuit having two normally open gaps therein, means for closing one gap in the control circuit when the temperature of the room falls beneath a chosen figure, means for closing the other gap in the control cir- 12o cuit when the furnace temperature or pressure falls beneath a chosen figure, and means 7 for closing the control circuit around both gaps at regular intervals of time.

6. The device of claim 5 in which the 12 periodic closing means includes a constantly rotating member, electric make and break devices opened and closed thereby, and a manually operated member for changing at will the length of the intervals of time between the eriodic short circuiting of the two gaps.

' 7. The device of claim 5 in which the periodic closing means consists of a constantly rotating drum having thereon a series of spaced contacts adapted to short circuit the two gaps and also a second series of contacts adapted to short circuit the gaps, one of said series of contacts being spaced further apart than the other and manually controlled means for shifting the relation of the contacts so as to complete the control circuit in shorter intervals or in lono'er intervals.

THOMAS H. BANFIELD. 

